I'd be happy to try to give you a civilized answer if I could understand your question. The focal lengths of 300, 400 , 500 and 600mm lenses are 300, 400, 500 and 600. That can't be what you were asking.

And as for "magnification" - what do you mean? The 600mm lens will be twice as "magnified" as a 300 which in turn is twice as magnified as a 150 lens would be (if there was such a thing as a 150mm lens). Edit - For the record, normal vision is often thought of as translating to somewhere about 50 to 60 mm, so if that is what you are asking, a 300mm lens would appear to be about 6 times "normal" vision.
You need to clarify your question in order to get a reply that will be useful to you.

It's not a dumb question Marc. I've often wondered that myself. Being an engineer, I should be able to give you a technically correct answer, but I haven't spent enough time studying optics. I believe that I've heard that a 300mm lens give a magnification of about 4 or 5 over the unaided eye.

Hopefully someone that does know optics will jump in here with a more knowledgeable answer.

ok, if the subject is 50 yards away, lookin thru a 400mm, can i determine how close the subject will be in the photo?

Click to expand...

If you know the angle of view of the lens (usually published by the manufactrer) as well as the subject size, then it should be a relatively straightforward trig problem to figure out the subject's size in the image. (though I confess I've not used any trig in years and would have to look up the formula).

what is the magnification, of each and the optimum focal length.

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Well this question is a bit confusing to me. Since we're talking about prime lenses here, the optimal focal length should be fairly obvious. :smile:

this conversation came up, we were talking about long lens, and how they were used for sports

i read a thread from some guy, who was talking about how to shoot sports like football and soccer.
he was responding to a question on fixed focal length lens and how do you determine the focal length, you need that will allow you to be most effective.
meaning in action oriented situations where the action is moving towards you and away from , what lens gives the greatest flexibilty.

so i thought about asking my question.

i have shot with all focal lenghts at one time or another, but have never thought about, there coverage, just kinda instinctive.
if you need longer lens then, that is why nikon (one reason) gave you the d2x hsc.
ok, need more help

1) So that they can achieve the 8 FPS that the D2H/Hs has (and that several high-end Canons have)

2) So that the file size will be smaller for those that don't need the full 12+MB image.

marc said:

flew, thanks

this conversation came up, we were talking about long lens, and how they were used for sports

i read a thread from some guy, who was talking about how to shoot sports like football and soccer.
he was responding to a question on fixed focal length lens and how do you determine the focal length, you need that will allow you to be most effective.
meaning in action oriented situations where the action is moving towards you and away from , what lens gives the greatest flexibilty.

so i thought about asking my question.

i have shot with all focal lenghts at one time or another, but have never thought about, there coverage, just kinda instinctive.
if you need longer lens then, that is why nikon (one reason) gave you the d2x hsc.
ok, need more help

Ok, here is a slightly different answer, that may be of some use. Others have commented on the math issues, and I would contend that many folks would not find anything having to do with trig a 'simple' matter :wink: , but let us look at this from the point of the view of the sports question you asked.

I shoot a lot of sports, mostly youth and high school, and generally I find that 300mm will get me players filling 60-70% of the frame at 30-40 yards, dependent on size and age of course. My 500mm gains me another 20 yards or so, and this really does limit what you can shoot and where, dependent, of course, on subject size. If I am shooting an American Goldfinch in my backyard for example, 25 feet or so from my door, my 500mm lens is perfect, my 300 adequate and my 70-200, well, lot's of crop to do :smile:

Now, back to the sports question for a moment. My "most-used" sports lens is my 120-300mm f2.8 Sigma. This range allows me to shoot players crossing the goal line from behind the end zone, and I can adequately capture action across the field. Best to be from 5-40 yards and the zoom allows me to capture much more of the "hot zone" than a fixed prime would. f2.8 enables me to shoot night games as well. It is a trade-off, for sure, and I often carry my D70 with the 18-70 for "really close" action. Now I just need to figure out how to switch quickly enough.

I have given this a little more thought, and have to basically agree with Paul. The only caveat would be that instead of saying that the eye has a 50mm field of view, I would say that on a camera with a viewfinder that shows approximately 100% of the sensor area (like a D2H or D2X), an image viewed with a 50mm lens doesn't look any more magnified than if you look directly at the subject. Now I know this may truly be splitting hairs, but to me it makes the magnification factors that Paul quoted more intuitive.

In any case, I agree with Paul's numbers. They may not be exact, but they are close. They are also easy to remember. :smile:

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